Why are information systems vulnerable to destruction, error, and abuse? List and describe the most common threats against contemporary information systems. Define malware and distinguish among a virus, a worm, and a Trojan horse. Define a hacker and explain how hackers create security problems and damage systems. Define computer crime. Provide two examples of crime in which computers are targets and two examples in which computers are used as instruments of crime. Define identity theft and phishing and explain why identity theft is such a big problem today. Describe the security and system reliability problems created by employees. Explain how software defects affect system reliability and security.